just wondering does it make that much difference in witch way the butterfly opens? just as I see it the air can only go out of the valves that are open and all so even though the turbo is blowing air in to the engine the piston is still sucking the air in like and N/A does, so carnt see it would make that much difference, but would like people thoughts on this

This is probably complete balderdash but..........In my head the current way is probably best. I can imagine air being deflected upwards, swirling around the roof of the chamber putting it on a nice trajectory to go down the runners.In my imagination reversing the butterfly will result in it swirling across the floor of the manifold and arriving at the ports travelling at 90 degrees to them

Given all the pressure waves and probable flow reversion in there its likely complete rubbish but there's always the old if it ain't broke principal (although you have a habit of fixing working stuff til it is broken lol)

I was just wondering as on a stock manifold witch is centre feed, the butterfly open down wards throwing air down into the manifold, but on the caldina manifold there throttle body opens up wards throwing the air up, so was just wondering if it did make any difference, I would of thought if it did make a difference it would only be when at part throttle, as when fully open there both flowing into the manifold the same way,

Years ago I'm sure I read somewhere that a Formula 1 team had cast direction arrows into the intake system so the air molecules know exactly which way to go Perhaps I should have checked if it was 1st April!

This is probably complete balderdash but..........In my head the current way is probably best. I can imagine air being deflected upwards, swirling around the roof of the chamber putting it on a nice trajectory to go down the runners.In my imagination reversing the butterfly will result in it swirling across the floor of the manifold and arriving at the ports travelling at 90 degrees to them

Given all the pressure waves and probable flow reversion in there its likely complete rubbish but there's always the old if it ain't broke principal (although you have a habit of fixing working stuff til it is broken lol)

errrm, unless I'm mistaken the throttle angles downwards as standard. On WOT the butterfly is pretty horizontal so wouldn't make any odds.

so would not that be the same on the centre feed? if the air was directed up into the manifold would that not do the same? just that on the 165-185-205 it opens down so throwing the air flow down, but as the air can only got out the valves that are open and pulled in by the pistons then surely it would not make any difference as all it doing is taking the pressured air from the chamber?

I'm not sure it will make any difference which way the throttle butterfly opens. I believe the airflow through the plenum reaches close to supersonic speeds at maximum power. As Sunny says, the plenum design is critical to good airflow distribution into the inlet runners. Toyota spent a lot of time, effort and money designing the plenums. I am sure the asymmetric layout is there for a purpose. My engine builder was always rather reluctant to consider using some of the aftermarket fabricated symmetrical plenums in case the feed to the runners might be uneven. This could result in some of the cylinders running lean with consequent risk of piston damage.

Just had a quick look at those (they are only visible to OC members). Most of the discussions are around the different plenum options rather than the throttle butterfly.

I did come across this interesting contribution from Dan:

Quote:

I've been doing a lot of playing with the CFD recently trying to find the nirvana of 3SGTE inlet manifolds, not a single one I've tested flows perfectly at all possible configuration i.e. if it flows well under boost, then it will be poor in n/a mode, even the variation in mass flow rate caused by changes in rpm have a big effect on how well the flow is balanced over all of the runners.